Editor's note: The recipe and introductory text below are from Aroma: The Magic of Essential Oils in Food and Fragrance by Mandy Aftel and Daniel Patterson.
This is an incredibly useful and versatile stock. It has a sweet vegetal flavor that can be used in many different ways—as a base for sauces and soups, adding richness and depth without changing the essential flavor of what it is paired with. It keeps in the refrigerator for one week, or you can freeze it indefinitely.

Chef Daniel Patterson of San Francisco's Coi shared this surprisingly easy recipe for making fresh butter and its delicious by-product—buttermilk—with Epicurious. The buttermilk can be used to make Patterson's Yuba "Pappardelle" with English Peas, Fava Leaves, and Basil .
Test-Kitchen Tip: Making butter can be an extremely messy process—as the buttermilk begins to separate, it will splash out of the bowl with each turn of the beaters. Even if your mixer has a splash guard, be sure to wrap sheets of plastic wrap from the rim of the bowl right over the top of the mixer (splash guard and all) to seal off any open spaces.

This light spring recipe, from chef Daniel Patterson of San Francisco's Coi, is a great way to use the buttermilk left over after making Patterson's homemade butter . Strips of yuba are simmered in the buttermilk and then topped with a bright-green sauce of fresh peas, basil, and fava leaves.
Yuba, also called tofu skin, is made by heating soy milk until a skin forms on the surface. Here, strips of tender, slightly chewy yuba stand in for pasta. (See the Test-Kitchen Tips, below, for more information on ingredients and substitutions.)